CN112425049A

CN112425049A - Motor and method for evaluating vibration state of motor

Info

Publication number: CN112425049A
Application number: CN201980047650.2A
Authority: CN
Inventors: J·施梅泽; D·舒贝尔
Original assignee: Ziehl Abegg SE
Current assignee: Ziehl Abegg SE
Priority date: 2018-07-17
Filing date: 2019-06-03
Publication date: 2021-02-26
Anticipated expiration: 2039-06-03
Also published as: US20210296977A1; SI3616308T1; RU2771573C1; JP2021530956A; CN112425049B; WO2020015796A1; DE102018211838A1; EP3616308B1; JP7266087B2; BR112020025470A2; EP3616308A1; ES2858449T3

Abstract

An electric motor is disclosed, comprising a stator (2), a rotor mounted so as to be rotatable relative to the stator, and motor electronics. The motor electronics are arranged in an electronics housing (7) and mounted on a circuit board (10). At least one vibration sensor (13) is arranged on the circuit board (10), the at least one vibration sensor (13) being configured to measure acceleration and/or speed of vibrations of the electric motor (1) in at least one direction. In addition, the circuit board (10) can be vibrationally coupled to other components of the electric motor (1) by means of at least one coupling element, so that at least parts of the vibrations of the electric motor are transmitted to the vibration sensor (13). Furthermore, a fan is disclosed comprising a motor according to the invention and an impeller. Furthermore, a method for evaluating a vibration state of an electric motor is disclosed, wherein the electric motor may be formed by an electric motor according to the invention.

Description

Motor and method for evaluating vibration state of motor

Technical Field

The invention relates to an electric motor having a stator, a rotor mounted so as to be rotatable relative to the stator, and motor electronics, wherein the motor electronics are arranged in an electronics housing and are mounted on a circuit board. The invention also relates to a fan with such a motor.

The invention also relates to a method for evaluating the vibration state of an electric motor.

Background

The motor is subjected to various types of vibration during its operation. These vibrations may be caused by the motor itself, by the driving load, or by the environment in which the motor is installed. For example, when the motor is a component of a fan, impeller imbalance or stall can produce vibrations. In addition, uneven drive torque, which may be caused, for example, by a pulsating DC bus voltage, may further exacerbate vibration. If the fan is installed in an industrial environment, vibrations from that environment may also be transmitted to the motor. The vibration may be even more pronounced if the fan is also operated at a rotational speed at which fan resonance occurs.

The motor or fan is typically dynamically balanced by reducing the asymmetric weight distribution or other vibration-producing conditions prior to delivery to a customer or prior to installation in a housing. However, damage may have occurred during installation in the enclosure, during shipping to the customer, during the customer application for installation, or during installation at the end customer, which may affect the balance quality. When the fan is operated in a fouled environment (e.g. in agriculture or under severely corrosive environmental conditions), the balance mass can also be affected over the life of the fan, since, for example, deposits or corrosion can affect the weight distribution.

The unbalance leads to increased vibrations, which in turn lead to heavy loads on the components of the motor. For example, bearings experience much more stress than less vibrating systems. High levels of vibration can result in the useful life of the motor and/or its components being significantly shortened. It is therefore worthwhile to measure the vibrations experienced by the motor.

EP 2972431B 1 discloses an electric motor having the function of monitoring the bearings of the motor. For this purpose, the vibration sensor is attached by a metal body sound element on the side of the stator flange facing away from the rotor. The vibration sensor measures vibrations from the motor. In this way, problems caused by the bearings of the motor can be identified. By attaching the vibration sensor to the stator flange, the vibration of the motor can be measured efficiently and reliably. However, attaching the vibration sensor to the stator flange is complicated and therefore expensive. Furthermore, strong impacts of the motor may damage the vibration sensor.

Disclosure of Invention

It is therefore an object of the present invention to configure and develop a motor, a fan and a method of the above-mentioned type in such a way that it is possible to reliably measure motor vibrations and/or reliably determine the state of motor vibrations at low cost.

According to the invention, the above object is achieved by the features of claim 1. The motor is thus characterized in that at least one vibration sensor is arranged on the circuit board, which vibration sensor is configured to measure acceleration and/or velocity of the motor vibrations in at least one direction, and that the circuit board can be vibrationally coupled to other components of the motor by means of at least one coupling element, such that at least parts of the vibrations of the motor are transferred to the vibration sensor.

With regard to the fan, the above object is achieved by the features of claim 14. The fan thus comprises a motor according to the invention and an impeller connected to the motor rotor.

With regard to the method, the above object is achieved by the features of claim 15. Thus, the method comprises the steps of:

generating a measurement signal by at least one vibration sensor, wherein the at least one vibration sensor is configured for measuring acceleration and/or velocity of motor vibrations in at least one direction,

determining the amplitude and/or phase and/or frequency of the measurement signal to determine at least one parameter of the motor vibration,

comparing the determined at least one parameter with a corresponding reference parameter, an

Determining a vibration state of the motor based on a result of the comparison of the determined at least one parameter with the corresponding reference parameter.

In accordance with the present invention, it is first recognized that it may not be necessary to attach a vibration sensor directly to the stator liner of an electric motor. Conversely, information about the vibration behavior of the electric motor can also be obtained by arranging a vibration sensor on a circuit board which is arranged in the electronics housing of the electric motor and which measures the acceleration and/or the speed of the vibration in at least one direction. It has been realized that the vibrations of the motor can be transmitted sufficiently well to the circuit board so that the vibrations of the motor can be measured by a vibration sensor arranged on the circuit board. However, various frequencies or ranges of the vibration spectrum may be attenuated or filtered by the circuit board or its fasteners. However, the amount of information of the vibration reaching the vibration sensor is large enough to enable information about the vibration behavior of the motor to be acquired. Thus, according to the invention, the vibration of the motor is not measured directly, but rather the vibration of the circuit board that is transmitted to the motor electronics. Since the motor electronics must be integrated into the electric motor anyway in one process step, there is no additional process step during the assembly of the electric motor when the vibration sensor is arranged on the circuit board of the motor electronics, so that the production costs are virtually unaffected by the vibration sensor.

So that there is a well-defined coupling between the vibration sensor and the other components of the motor according to the invention, at least one coupling element being used to vibrationally couple the circuit board and/or the vibration sensor with the other components of the motor. If the relation between the vibration of the motor and the measured values collected by the vibration sensor is known, for example, by means of calibration measurements, conclusions about the vibration behavior of the motor can be drawn from the measured values.

The "other components of the electric motor" between which the at least one coupling element is intended to improve the transmission of vibrations may be formed by various components of the electric motor. By way of example only, and not limitation, "other components of the motor" may be formed by stator bushings, motor housings, bearing tubes, stator coil packages, fixtures of the motor or electronics housing.

On the circuit board on which the vibration sensor is arranged, the motor electronics can fulfill various functions. In the simplest case, the motor electronics can be formed by a circuit board with connecting conductors and pads. Such a circuit board can be used, for example, for connecting the individual coils of the stator to one another. Preferably, however, the motor electronics also comprise additional electrical and/or electronic components. In this case, the motor electronics can comprise a simple sensor which provides a sensor signal, for example for the rotational speed, to an external control device of the electric motor. The motor electronics can also assume control tasks and/or comprise a power supply section. Very particularly preferably, however, the motor electronics supply the stator winding and/or the rotor winding with a power supply signal. For this purpose, the motor electronics can have a supply voltage input, in which a supply voltage (for example a DC voltage or a three-phase system) is input. The motor electronics then generate a series of power supply signals from the input power supply voltage, which power supply signals cause the rotor of the electric motor to perform a rotational movement.

In principle, the circuit board can also be made of various materials. However, the circuit board is preferably made of a rigid composite material with the conductor tracks applied thereon. Typically, such circuit boards are made of fiber reinforced plastic. The circuit board may have conductor tracks on several layers, for example on the top side and the bottom side, and optionally also in one or more intermediate layers interposed between the top side and the bottom side. Corresponding circuit boards are well known in practice.

The vibration sensor may be formed in various ways. It is important that the vibration sensor is capable of providing an acceleration and/or velocity value of the measured vibration. Here, the vibration sensor may be formed of a MEMS (micro electro mechanical system) acceleration sensor, a piezoelectric acceleration sensor, a microphone (e.g., a MEMS microphone), or a strain gauge. Suitable sensors for this purpose are well known in practice.

As already mentioned, the vibration sensor is configured to measure acceleration and/or velocity of the motor vibration in at least one direction. There may be configurations where measurements in only one direction are sufficient. This may be the case, for example, when the motor tends to exhibit particularly strong vibrations in said one direction, while the other direction develops a relatively lesser tendency to vibrate. Preferably, however, the vibrations are measured in several directions, particularly preferably in three directions, wherein the respective directions are not parallel to each other. The choice of the direction in which the vibration is measured may depend on the vibration mode in which the motor normally vibrates. However, in a preferred configuration, in which the directions of the measurement vibrations are formed perpendicular to each other, the three directions form, for example, a classical cartesian coordinate system. In this case, for example, the first direction may be parallel to the axis of the motor, while one of the other directions is arranged parallel to the reference plane of the motor.

When measuring vibrations in several directions, a single vibration sensor configured to measure in the respective desired direction may be used. Thus, for example, in practice it is known that vibration sensors are capable of measuring vibrations arranged in three directions perpendicular to each other. However, the vibration sensors may also be formed by a family of vibration sensors, each of which covers one of several directions. This configuration is particularly useful when the directions in which vibrations are to be measured are not perpendicular to each other. Any number of axis constellations can be generated using this family of vibration sensors. If the individual vibration sensors in the family are arranged close to each other on the circuit board, the measurement of the family of vibration sensors differs only negligibly from the measurement of the individual vibration sensors.

In principle, the electronics housing can be arranged at various positions of the electric motor. It is only important that the electronics housing be vibrationally coupled to the other components of the motor. This can be achieved in a simple manner, since the electronics housing is integrated in the electric motor or is attached to the outside of the motor housing. In the second case mentioned, the electronics housing can be realized, for example, as a separate, closed electronics tank which is flanged to the motor housing. The electronics housing is preferably arranged on the stator bushing of the electric motor, i.e. the motor electronics is arranged near the axis of the shaft, in which case the circuit board is usually arranged perpendicular to the shaft axis.

Furthermore, it is not at all relevant whether the motor electronics inside the electronics housing are accessible after the motor is finished. Since the motor electronics in existing electric motors are usually molded from a casting compound, the motor electronics are generally not directly accessible anyway. It is even possible to such an extent that the electronics housing is completely encapsulated by the overmolding material so that the electronics housing as well as the electromechanical electronics are virtually inaccessible without damage. Even such an electronics housing would meet the requirements of the present invention as long as there is vibration coupling between the vibration sensor and the other components of the motor.

In principle, the electronic device housing may have a wide variety of shapes. However, the electronic device housing preferably has a bottom and side walls. In the electronic device case constructed in this way, the circuit board is arranged substantially parallel to the bottom of the electronic device case. In its simplest configuration, this electronic device housing is cup-shaped with a circular bottom surface. However, the bottom surface may have other shapes. Regular shapes (such as, for example, square, rectangular, hexagonal, or octagonal) may also be used as irregular shapes. Also, the sidewalls do not necessarily have to be perpendicular to the bottom. Such electronic device housings are typically closed by a cover that closes an open area of the electronic device housing. In this case, the cover may be arranged, for example, parallel to the bottom.

In one configuration, the vibration sensor is arranged on a side of the circuit board facing away from the bottom of the electronic device housing, i.e. on a top side of the circuit board. This configuration has the following advantages, in particular in the case of strong shock stresses of the motor: the gap between the electronic device housing and the vibration sensor shape is relatively large.

In another configuration, the vibration sensor is arranged on a side of the circuit board facing away from the bottom of the electronic device housing, i.e. on a top side of the circuit board. This configuration provides the following advantages: vibrations in the case of a corresponding coupling between the bottom and the vibration sensor are more easily and efficiently conducted to the vibration sensor and in this way more accurate measurements can be made.

In principle, it is also conceivable, in particular in a family of vibration sensors, for the first part of the vibration sensor to be on the top of the circuit board and for the second part of the vibration sensor to be arranged on the bottom of the circuit board.

Regardless of whether the at least one vibration sensor is arranged on the top and/or bottom of the circuit board, the bottom of the electronic device housing may comprise a protrusion in the area of the at least one sensor such that the distance between the at least one vibration sensor and the electronic device housing is shortened. Here, preferably, the protrusion is formed to be flat at a top side thereof. In this context, "in the area of the vibration sensor" means that there is significant overlap between the one or more vibration sensors and the protrusion of the bottom of the electronic device housing when the top of the circuit board is viewed. The protrusion does not necessarily have to extend over the entire surface spanned by the at least one vibration sensor. However, to avoid deformations, it is useful that the protrusion is at least as large as the vibration sensor (or in the case of several vibration sensors the area spanned by these vibration sensors).

For the arrangement of the vibration sensor on the circuit board, it may be advantageous to know the waveforms that occur in various applications. Thereby, the vibration sensor may be positioned and its measurement direction may be aligned such that the generated measurement signal provides a clear and distinguishable depiction of the vibrations and vibration modes.

In principle, the coupling element can be made of various materials. It is important that the coupling element transmits vibrations better than air and in this way an improved coupling between the vibration sensor and other components of the motor can be established. However, it is recommended that there is no direct metallic coupling between the vibration sensor and the other components of the motor, since on the one hand the metal conducts vibrations very well, while on the other hand the metal provides practically nonexistent damping in the case of strong vibrations. The at least one coupling element is therefore preferably made of a plastic which additionally improves or establishes the electrical insulation of the sensor.

In one configuration, the at least one coupling element includes a casting material that fills at least a portion of a gap between the electronic device housing and the circuit board. When the electronic device housing has a bottom and side walls, this gap may be formed, for example, between the bottom and the circuit board. Such casting compounds are widely used in electrical and electronic devices and are generally based on plastics. For example, the casting compound facilitates heat dissipation toward the electronics enclosure and stabilizes the electromechanical electronics in the electronics enclosure.

In a modification of this configuration, a separating wall may be provided which separates the casting compound into a first casting compound and a second casting compound. This is useful in case the partition wall is also made of a non-conductive material, preferably plastic. In this modification, the second casting compound has a lower elasticity than the first casting compound, i.e. the second casting compound is "harder" than the first casting compound. In addition, a second casting compound is arranged on the vibration sensor. The division into a first and a second casting material has the following advantages: in the region of the vibration sensor, a casting compound can be used which advantageously transmits vibrations to the vibration sensor, while in the other region, for example, a casting compound which in particular enables good heat dissipation can be used.

In another embodiment, the at least one coupling element comprises a sticky pad or adhesive interposed between the vibration sensor and a portion of the electronic device housing. In this way, the vibration sensor can be relatively fixedly coupled to other components of the motor while still maintaining a simple mounting when the circuit board is inserted into the electronics housing. The adhesive may be configured as a hardened adhesive, for example, based on epoxy. Preferably, the adhesive pad and the adhesive have electrically insulating properties, i.e. low electrical conductivity.

In another configuration, at least one coupling element comprises a plastic overmold material that is attached to at least portions of the motor. In the case of electric motors, it is not uncommon for the components of the motor to be overmolded and connected to the plastic during the injection molding process. Thermoplastic or thermoset materials are often used herein. In this way, for example, parts of the wound laminated stack of the stator and parts of the housing of the electronic device can be connected by overmoulding. In this case, the bearing seat may be part of the package insulator or part of the overmold material. In such cases, the overmold material may form a coupling element within the meaning of the present invention. An additional coupling element, for example in the form of an adhesive pad, may be attached between the vibration sensor and the overmoulded material. However, the plastic overmold material is preferably in direct contact with the at least one vibration sensor.

In another configuration, the at least one coupling element comprises a (mechanical) fastener mechanically and/or electronically connecting the circuit board to another part of the motor. In this case, the fastener may be formed of various means capable of producing a mechanical connection and a vibration coupling. Removable as well as non-removable fasteners may be used. By way of example only and not limitation, reference is made to the use of screws, rivets, clamps, pins, grooved nails, and the like. The type of coupling is accomplished differently depending on the fastener used. In this case, a fastener, for example configured as a screw, may be passed through a hole in the circuit board and screwed into a thread of the electronic device housing. To further improve the vibration coupling between the vibration sensor and other components of the motor, it is useful that the fastener is arranged in the vicinity of the vibration sensor. This means that when the circuit board is viewed, the distance between the fastener and the vibration sensor is much smaller compared to the size of the circuit board. Preferably, the distance is at most 20% of the size of the circuit board, particularly preferably at most 10% of the size. At the same time, it is not recommended to fall below a certain minimum distance between the fastener and the vibration sensor. The distance is preferably at least 5% of the size of the circuit board.

The above-described configurations of the at least one coupling element may be combined relatively arbitrarily. Some examples in which the respective elements of the above-described coupling elements are combined with each other are explained in more detail in the following exemplary embodiments. Those skilled in the art will recognize that the various configurations of the coupling elements can also be combined in other ways and how.

In another development, the electronic device housing may be completely or partially coated with plastic, or a plastic liner may be placed in the electronic device housing. This development can be used, for example, to improve isolation between the motor electronics and the electronics housing. In the case of an electronic device housing having a bottom and side walls, the bottom and/or side walls may be coated or covered, for example with plastic. It is also conceivable that only a part of the bottom or a part of the side wall is coated with plastic or covered with a plastic lining.

In principle, the electric motor can be configured in various ways. It is only important that there be motor electronics to which the vibration sensor can be attached. However, in a preferred configuration, the electric motor is formed by an EC motor (electronically commutated motor), wherein the motor electronics generate a family of power supply signals capable of generating a rotating field in the electric motor that rotates the rotor. The EC motor can be designed here as an internal or external rotor design.

The method according to the invention can be used to evaluate the vibration state of an electric motor. In this case, the motor may be formed of the motor according to the present invention. In the method according to the invention, in a first step, a measurement signal is generated by at least one vibration sensor, which measurement signal represents the speed and/or acceleration of the vibration of the electric motor in at least one direction. In this case, the measurement signal preferably comprises time-and frequency components in the frequency spectrum.

In a further step, the measurement signal is analyzed, wherein the amplitude and/or the phase and/or the frequency of the measurement signal is determined for determining at least one parameter of the vibration of the electric motor. The amplitude of the measurement signal refers to the range over which the measurement signal moves. In the simplest case, the amplitude is the maximum quantity taken by the measurement signal in the measurement period under consideration. However, it is also conceivable to consider the amplitude as the value that the measurement signal takes on average over the measurement period under consideration. The frequency of the measurement signal refers to the spectral components of the measurement signal. Here, "frequency of the measurement signal" may refer to a single dedicated frequency, several dedicated frequencies, or one or more frequency ranges. The phase of the measurement signal refers to the time relation between several sub-areas of the measurement signal. The phase can relate here, for example, to the relationship between the active and reactive components of the measurement signal. However, when measuring vibrations in several directions, the phase preferably refers to the time relation between the measurement signals in the respective directions. The magnitude and form of the motor vibrations can be deduced from the amplitude, phase and/or frequency of the measurement signal. Thereby, in this way, at least one parameter of the vibration of the motor may be determined.

In a next step, the at least one parameter determined in this way is compared with a corresponding reference parameter. This means that for example the magnitude of the measured quantity is compared with a reference magnitude (e.g. the maximum permitted magnitude). Several parameters can also be compared with several respectively corresponding reference parameters. By combining several parameters, a more comprehensive picture of the vibration state of the motor can be determined than would be possible with a single parameter.

In a further step, a vibration state of the electric motor is determined from a comparison of the determined at least one parameter with one or more corresponding reference parameters. Knowledge of the vibration behavior of the motor (e.g. from calibration measurements) or knowledge of structurally equivalent or very similar motors may be used here.

In a further development of the method according to the invention, a warning message is generated and/or measures for protecting the electric motor are initiated on the basis of the determined vibration state. In principle, various reactions to specific vibration states can be envisaged. The warning message may indicate that the maximum allowable vibration value has been reached or exceeded. However, the warning message may also signal the presence of a particularly unfavorable vibration pattern that causes a heavy load on the motor. How the warning message is output depends on the corresponding application scenario. It is conceivable to send corresponding warning messages over the network, in particular in an industrial 4.0 environment. The warning message may be received, for example, by a maintenance person or an operator, and appropriate countermeasures may be taken. Warning messages may also be output by simple light emitting diodes, for example green for normal operation and red for adverse vibration patterns. It is also conceivable here for example that the light-emitting diode lights up orange when a first oscillation limit value of the light-emitting diode is exceeded. The warning message can also be used in particular in the case of dirt-laden environments to trigger cleaning and/or maintenance work.

Alternatively or additionally, measures to protect the motor may be initiated based on the determined vibration pattern. These measures may include, for example, changing the rotational speed of the motor. In most cases, reducing the rotational speed may help reduce vibration. In this way, the electric motor can be placed in an operating state with less vibrations. Another measure may include switching control to a quieter mode of operation by, for example, more strongly compensating for fluctuations in drive torque.

In one configuration, it can be checked whether at least one parameter exceeds a predefined limit value before comparing it with a (respectively) corresponding reference parameter. For example, a threshold value may be defined that the measurement signal amplitude must exceed at least before other steps are performed. If the measurement signal does not reach the threshold, the steps of comparing and determining the vibration state may be skipped to save computational resources.

The following outlines some functions and developments, which can be performed by the electric motor according to the invention, the fan according to the invention and the method according to the invention.

1) Vibration values of the motor electronics are collected for protecting the electronic components, for example by adjusting the rotational speed/closing at a critical value. Because the sensor is directly attached to the electronics, vibrations impacting the motor electronics can be directly measured and possible damage to the electronics can be estimated. This can also be achieved with separate (external) power and control electronics/frequency converters.

2) Vibration values of the entire system are collected by coupling a motor, fan, or electronics with customer-side components such as heat exchangers, ventilation ducts, heat pumps, air handling boxes, etc. The resonance of the entire system can be made weaker by setting a rotation speed at which the vibration is reduced and which is slightly different from the target rotation speed.

3) Transport damage is detected by comparing the vibration values of the fan at the customer during start-up with a stored reference curve for the final test (pre-delivery) of the fan. In the event of exceeding a limit value, a warning message is output.

4) After start-up, it is determined that the imbalance due to fouling or corrosion is slowly increasing (e.g., over a long period of time, such as weeks or months). A warning message or indication regarding required fan cleaning may be output and a cleaning or maintenance interval determined.

5) The wear state of the bearing seats in the stator liner is calculated/estimated based on the vibration amplitude and/or frequency, vibration mode, rotational speed, mounting position, rotational mass and/or run time (load profile).

6) A possible warning message output or a possible speed adjustment is used to identify a fan stall to exit the critical operating state. Fan operation in the stall region typically results in more noise being developed, pulsating airflow near the fan, and higher vibration levels than normal operation. When the fan is operating in the stall region, the blades begin to vibrate at their natural frequency. If this condition persists for a longer period of time, the blade may break due to fatigue.

7) The resonance and/or associated vibration modes of the entire system are identified. In coordination with the placement and alignment of the sensors, specific vibration modes may be identified with the aid of amplitude and phase information identification of the sensor signals. This means that modal analysis can be performed during operation, which allows linking the rotational speed and/or the load state of the electric machine to critical vibration events. Operation in or near these states has a negative impact on the useful life of the application. Warning messages or active measures, such as active fading out of the respective critical speed ranges, can then be output.

8) Vibration values of the customer environment are collected by coupling the motor/fan or electronics with customer-side components (such as heat exchangers, ventilation ducts, heat pumps, air handling boxes, etc.) while the motor/fan is at rest. When the motor is at rest, disturbing vibrations from the customer's environment affecting the motor/fan may be collected and stored. This measurement can be done at specific time intervals when the motor is stationary and can be used in particular for assessing the installation situation or for damage diagnosis. At very high vibration values, a warning message may be output even before the fan is started.

Drawings

There are now various possibilities to configure and develop the teachings of the present invention in an advantageous manner. To this end, reference is made, on the one hand, to the claims depending on the independent claims and, on the other hand, to the following description of preferred exemplary embodiments of the invention with reference to the accompanying drawings. In connection with the explanation of the preferred exemplary embodiments of the invention by reference to the drawings, also a general preferred configuration and further developments of the present teaching are explained. In the drawings:

fig. 1 shows a cross section of a first exemplary embodiment of an electric motor according to the invention, screws and casting compound being used as coupling elements;

fig. 2 shows a cross-section of a second exemplary embodiment of an electric motor according to the invention, similar to the first exemplary embodiment, in which the bottom and the side walls of the housing of the electronic device are additionally coated with plastic;

fig. 3 shows a cross section in a third exemplary embodiment of an electric motor according to the invention, in which the bottom of the electronics housing has a projection in the region of the vibration sensor;

fig. 4 shows a cross section in a fourth exemplary embodiment of an electric motor according to the invention, in which parts of the bottom and the side walls of the electronics housing are covered with plastic and in which a casting compound is used as coupling element only in the partial region between the bottom of the electronics housing and the circuit board;

fig. 5 shows a cross section in a fifth exemplary embodiment of an electric motor according to the invention, screws, casting compound and adhesive pads being used as coupling elements;

fig. 6 shows a cross section in a sixth exemplary embodiment of an electric motor according to the invention, in which the casting compound is divided by a partition wall into a first and a second casting compound;

fig. 7 shows a cross-section of a seventh exemplary embodiment of an electric motor according to the invention, a screw and a plastic overmoulding material being used as coupling element;

fig. 8 shows a cross-section of an eighth exemplary embodiment of an electric motor according to the invention, a plastic overmoulding material being used as the coupling element;

FIG. 9 shows a graphical representation of exemplary curves for vibration values at different rotational speeds during measurement of a vibration sensor in different directions; and

fig. 10 shows a flow chart of an exemplary embodiment of a method according to the present invention.

Detailed Description

All exemplary embodiments of the electric motor according to the invention shown in the figures are each constructed in an external rotor design. This means that the stator is arranged at the motor shaft and the rotor is arranged around the stator. For simplicity, the rotor of the motor is not shown in each of the figures. This of course does not mean that the motor does not have a rotor.

In each case, fig. 1 to 6 show a cross section in a stator 2 of an electric motor 1 according to the invention. A bearing tube 4 is formed at the motor shaft 3, with a bearing receiving area 5 being formed in each case at the longitudinal end of the motor shaft 3. The bearing receiving area 5 accommodates a bearing (not shown), whereby a shaft (not shown) of the electric motor can be rotatably mounted. The stator bush 6 is formed by an aluminium component, at one end of which stator bush 6 a bearing tube 4 is formed and at the other end of which stator bush 6 an electronics housing 7 is formed for accommodating the motor electronics. The electronics housing 7 has a bottom 8 and side walls 9. The motor electronics generate and output a power signal to the stator and/or rotor windings. For the sake of simplicity, fig. 1 to 6 only show the circuit board 10 of the motor electronics. In the following, the side of the circuit board 10 facing the bottom 8 is referred to as the bottom side 11 and the side of the circuit board 10 facing away from the bottom 8 is referred to as the top side 12. The various exemplary embodiments of the electric motor according to the invention shown in fig. 1 to 6 differ in the arrangement of the vibration sensor 13 on the circuit board 10 and the coupling elements used in each case.

In the exemplary embodiment of fig. 1, the vibration sensor 13 is arranged on the top side 12 of the circuit board 10. The printed circuit board 10 is embedded in a casting

compound

14, 15, wherein the casting

compound

14, 15 is connected to an edge region of the printed circuit board 10. In this case, in particular, the part of the casting compound 14 enclosed between the bottom 8 and the underside 11 of the circuit board 10 serves as a coupling element within the meaning of the invention and transmits the vibrations from the stator lining 6 via the bottom 8 of the electronics housing 7 to the circuit board 10 and thus to the vibration sensor 13. As additional coupling elements screws 16 are provided which are screwed into holes 17 in the housing 7 of the electronic device. In the exemplary embodiment shown, the screws are arranged close to the vibration sensor 13 and thus also ensure that vibrations are transmitted from the stator bush 6 to the circuit board 10 and thus to the vibration sensor 13 via the screws 16.

The exemplary embodiment of fig. 2 is very similar to the exemplary embodiment of fig. 1. In addition, however, the plastic coating 18 is attached to the bottom 8 of the electronic device housing as well as to portions of the side walls 9. The plastic coating 18 provides additional electrical insulation, but also transmits motor vibrations to the casting compound 14 (in this case vibrations from the bottom 8 of the electronics housing 7). Thus, even this plastic coating 18 can form a coupling element within the meaning of the present invention.

In the exemplary embodiment of fig. 3, the vibration sensor 13 is arranged on the bottom side 11 of the circuit board 10. In the exemplary embodiment, casting

compound

14, 15, screw 16 and plastic coating 18 are used as coupling elements. In order to shorten the distance between the bottom 8 of the electronics housing 7, a projection 19 is formed in the region of the vibration sensor 13. The projection 19 is slightly wider than the extent of the vibration sensor 13 and is planar on the top side. Between the projection 19 and the vibration sensor 13, there is still some casting compound 14 and plastic coating 18.

In the embodiment of fig. 4, a partition wall 20 is formed, which partition wall 20 is formed integrally with a plastic lining 28 in the exemplary embodiment shown. Similar to the plastic coating 18 of fig. 2 or 3, a plastic liner 28 covers portions of the bottom 8 and the side wall 9. The partition wall 20 separates the regions in which the casting compound 14 is arranged as coupling elements. The other regions between the circuit board 10 and the bottom and the regions above the circuit board 10 are not filled with the casting compound. As a further coupling element, there is likewise a screw 16 which is arranged close to the vibration sensor 13. In this exemplary embodiment, a screw 16 is placed between the motor shaft 3 and the vibration sensor 13.

The exemplary embodiment of fig. 5 comprises casting compounds 14, 15 and screws 16 as coupling elements. Further, a protrusion 19 is formed at the bottom 8, which shortens the distance between the bottom 8 and the vibration sensor 13. In addition, an adhesive pad 21 is arranged as a further coupling element, which adhesive pad 21 fills the area between the vibration sensor 13 and the protrusion 19 and establishes an additional vibration coupling between the vibration sensor 13, the circuit board 10 and other components of the motor.

In fig. 6, a separating wall 20 is likewise provided, in which case the separating wall 20 separates the casting compound between the base 8 and the printed circuit board 10 into a first casting compound 22 and a second casting compound 23. In this case, the second casting compound 23 has a lower elasticity than the first casting compound 22, so that the second casting compound 23 is "harder" than the first casting compound 22. In this way, the second casting compound 23 will establish a better coupling between the vibration sensor 13 and the other components of the motor, which is expressed in particular by a better transmission of higher frequencies.

Fig. 7 shows another exemplary embodiment of an electric motor according to the present invention. In this case, the electronic device housing 7 is formed by an aluminum component 24 having a bottom 8 and a side wall 9. In the bottom 8, a hole (not shown) is formed through which the plastic overmolding material 25 may penetrate during the injection molding process. The plastic overmold material connects the stator 2 to the electronics housing 7 and is configured as BMC (bulk molding compound). The plastic overmoulding material is in direct contact with the vibration sensor 13 and serves as a coupling element within the meaning of the present invention. In addition, a screw 16 is present as an additional coupling element, which screw is screwed into the thread of the aluminum component 25.

Fig. 8 shows a relatively similar construction, in this case the electronics housing 7 does not have aluminum components, but the electronics housing 7 is formed from the plastic overmold material 25 itself. Here, too, the plastic overmoulding material 25 forms a coupling element within the meaning of the invention, and the vibration sensor 13 is in direct contact with the plastic overmoulding material. In addition, a cover 26 is shown closing the open side of the electronic device housing. The cover 26 is attached to the plastic overmold material by screws 27.

Fig. 9 shows diagrams of different signal curves that can be generated on a vibration sensor of an electric motor. Such a vibration sensor may be, for example, the vibration sensor 13 in the motor of the previously described exemplary embodiment. In this case, the three signal curves shown represent exemplary measurement signals of the vibration sensor in three different directions. In this case, the three directions are respectively formed perpendicular to each other. The solid line represents the measurement signal in the first sensor axis, the dashed line represents the measurement signal in the second sensor axis, and the dashed line represents the measurement signal in the third sensor axis. The rotational speed is displayed on the abscissa and the magnitude of the measured value is displayed on the ordinate. It can be seen that different signal curves are formed in different sensor shafts at different rotational speeds. These differences in different directions can be used for the method according to the invention, for example for the method shown in fig. 10.

Fig. 10 shows a flow chart of an exemplary embodiment of a method according to the present invention. In a first step 30, measured values of the sensor are collected in at least one direction. In the exemplary embodiment, the measured values are collected over three directions/sensor axes. In step 31, these measured values are analyzed and the amplitude, phase and frequency of the measurement signal are calculated. This produces a parameter of the motor vibration. At step 32, the calculated amplitude is compared to a reference amplitude. In the event that the magnitude of the measurement signal in all sensor axes does not exceed the threshold, further processing is aborted and a new data collection is returned to step 30. If the amplitude of the measurement signal in a sensor axis exceeds the threshold value, additional steps are performed.

In step 33, the determined measured values and/or the calculated parameters are matched to the vibration state of the known vibration pattern, i.e. the determined parameters are compared with reference parameters, which have been recorded in each case in the known vibration pattern. These reference parameters may come from a database whose contents have been created in the calibration measurements of the motor. Alternatively, the database may also contain reference parameters of structurally equivalent or at least similar electric motors. From which it can be deduced in which vibration state the motor is currently in.

In step 34, the rotational speed, for example, is slightly reduced in response to the identified vibration condition. At step 35, wait until the change is in effect and the system has moved to steady state. This typically occurs in seconds to minutes. The method then repeats at step 30 and a new data collection is performed.

With regard to other advantageous configurations of the electric motor according to the invention or of the method according to the invention, reference is made to the general part of the description and to the appended claims in order to avoid repetitions.

Finally, it should be expressly noted that the above-described exemplary embodiments are merely illustrative of the claimed teachings and do not limit the teachings to exemplary embodiments.

List of reference numerals

1 Motor (rotor not shown)

2 stator

3 Motor shaft

4 bearing tube

5 bearing receiving area

6 stator bush

7 electronic equipment shell

8 bottom

9 side wall

10 circuit board

11 bottom side

12 top side

13 vibration sensor

14 casting material

15 casting material

16 screw

17 holes

18 plastic coating

19 projection

20 partition wall

21 sticky pad

22 first casting material

23 second casting compound

24 aluminium assembly

25 Plastic overmoulded Material

26 cover

27 fastening screw

28 Plastic liner

Claims

1. An electric motor having a stator (2), a rotor rotatably mounted relative to the stator, and motor electronics, wherein the motor electronics are arranged in an electronics housing (7) and mounted on a circuit board (10),

at least one vibration sensor (13) is arranged on the circuit board (10) and configured to measure acceleration and/or velocity of vibrations of the electric motor (1) in at least one direction, and the circuit board (10) is vibrationally coupleable to other components of the electric motor (1) by at least one coupling element such that at least parts of the vibrations of the electric motor are transferred to the vibration sensor (13).

2. The motor according to claim 1, characterized in that the electronics housing (7) has a bottom (8) and preferably side walls (9).

3. The electric motor according to claim 2, characterized in that the at least one vibration sensor (13) is arranged on a side of the circuit board (10) facing the bottom (8) of the electronics housing (7).

4. The electric motor according to claim 2 or 3, characterized in that the bottom (8) of the electronics housing (7) has a projection (19) in the region of the at least one vibration sensor (13) so that the distance between the at least one vibration sensor (13) and the electronics housing (7) is shortened.

5. The motor according to any one of claims 1 to 4, characterized in that said at least one coupling element is made of plastic.

6. The electric motor according to any of the claims 1 to 5, characterized in that the at least one coupling element comprises a casting compound (14, 15, 22, 23) filling at least parts of the area between the electronics housing (7) and the circuit board (10).

7. The electric motor according to claim 6, characterized in that the casting compound is divided by a partition wall (20) into a first casting compound (22) and a second casting compound (23), the second casting compound (23) having a lower elasticity than the first casting compound (22), and wherein the second casting compound (23) is arranged at the vibration sensor (13).

8. The electric motor according to any of the claims 1 to 7, characterized in that the at least one coupling element comprises an adhesive pad (21) or an adhesive.

9. The electric motor according to any of the claims 1 to 8, characterized in that the at least one coupling element comprises a plastic overmoulding material (25) attached to at least parts of the electric motor (1), wherein the at least one vibration sensor (13) is preferably in direct contact with the plastic overmoulding material (25).

10. The electric motor according to any of the claims 1 to 9, characterized in that the at least one coupling element comprises a fastener, preferably formed by a screw (16), a rivet, a clamp, a pin, or a slotted nail, which is preferably arranged close to the vibration sensor (13).

11. The electric motor according to any of the claims 1 to 10, characterized in that the electronics housing (7) is formed on a stator bushing (6) of the electric motor (1).

12. The electric motor according to any of the claims 1 to 11, characterized in that the electric motor (1) is formed by an EC motor, an electronically commutated motor.

13. The motor according to any of the claims 1 to 12, characterized in that the electronics housing (7) has a bottom (8) and a side wall (9), and that the bottom (8) and/or the side wall (9) is coated or covered with plastic (18).

14. A fan having a motor as claimed in any one of claims 1 to 13 and an impeller connected to the rotor of the motor.

15. Method for evaluating the vibration status of an electric motor, in particular an electric motor according to any of claims 1 to 13, comprising the steps of:

generating a measurement signal by at least one vibration sensor, wherein the at least one vibration sensor is configured to measure acceleration and/or velocity of vibrations of the electric motor in at least one direction,

determining the amplitude and/or phase and/or frequency of the measurement signal to determine at least one parameter of the vibration of the motor,

16. The method of claim 15, wherein based on the determined vibration state, generating a warning message and/or initiating a measure to protect the motor.

17. Method according to claim 15 or 16, characterized in that it is checked whether the at least one parameter exceeds a predefined limit value before comparing the determined at least one parameter with the corresponding reference parameter.